The embodiments disclosed herein relate generally to a screw pump, and more particularly to lubrication and process fluid management of a multiphase screw pump.
Screw pumps are rotary, positive displacement pumps that use two or more screws to transfer high or low viscosity fluids or fluid mixtures along an axis. In an embodiment, a twin screw pump may have two intermeshing counter-rotating rotor screws. The volumes or cavities between the intermeshing screws and a liner or casing transport a specific volume of fluid in an axial direction around threads of the screws. As the screws rotate the fluid volumes are transported from an inlet to an outlet of the pump. In some applications, twin screw pumps are used to aid in the extraction of oil and gas from on-shore and sub-sea wells. Twin screw pumps lower the back pressure on the reservoir and thereby enable greater total recovery from the reservoir.
In many cases, the twin screw pump may be used to pump a multiphase fluid from a sub-sea well which may be processed to produce the petroleum products. Accordingly, twin screw pumps may be configured to prevent the flow of process fluids into the bearings, timing gears, motor, environment, or the like. In particular, twin screw pumps may utilize a shaft seal on each end of each rotor, thereby requiring four seals in total. The shaft seals also typically require the usage of a lubricant flush system that maintains the rub surfaces of the sealing system clean and removes heat from the sealing surfaces.
Further, in the example the system used to lubricate the various parts of the twin screw pump system, including bearings coupled to the rotor screws, may require additional components and maintenance. This separate lubrication system adds costs and maintenance to the screw pump system.